Regulating water decontamination and food safety by a reusable, nano-sized MOF@cotton@chitosan composite through nanomolar detection of the drug nitroxinil and organoarsenic feed additive p-arsanilic acid

Abstract

Food safety and security are emerging challenges in the modern era. To resolve such challenges, numerous pesticides, drugs and feed additives are used to harvest foodstuffs. Among these, some are very toxic to human beings and the environment. Therefore, knowing their presence in foodstuffs and measuring their concentrations are crucial. To address such challenges, herein, a formamide-functionalized, reusable, nano-sized and eco-friendly Hf(IV)–organic framework (1) is developed. After synthesis and characterization of the porous framework (S_BET = 555 m² g⁻¹), it was used for selective and fast fluorescence sensing of the extensively used anthelmintic veterinary drug nitroxinil (NX) and the organoarsenic feed additive p-arsanilic acid (PAA) in aqueous medium through a turn-off and turn-on response, respectively. This fluorescent metal–organic framework (MOF) is the first ever reported sensor for both these analytes, and can detect them within a few seconds (5 s for NX and 15 s for PAA) of their addition, with limit of detection values of 11.8 nM and 17.2 nM for NX and PAA, respectively. The calculated LOD values are the lower than for all the previously reported sensors for both analytes. With high reusability, high selectivity and very short response time, the probe can sense the presence of the targeted analytes in body fluids (for NX), chicken flesh and liver extracts (PAA), environmental water and soil samples and a wide range of pH media, with equal efficiency. For rapid and on-site, naked-eye detection of both targeted analytes, an economical, handy, recyclable and biocompatible MOF@chitosan@cotton composite was fabricated. The composite was capable of changing colour up to nanomolar concentrations for both analytes. With proper instrumental support, systematic investigation of the probable mechanisms of both sensing events were investigated.